This invention relates to a method of an apparatus for supplying natural gas fuel for the purposes of heating or power generation. The method and apparatus according to the invention are particularly suitable for use on board ship for the purpose of providing fuel to the ship's engines.
EP 1 291 576 A relates to apparatus for supplying natural gas fuel (the principal component of which is methane) to heat the boilers of an ocean-going tanker for the transport of LNG. The apparatus comprises a compressor having an inlet communicating with the ullage space of at least one LNG storage tank and an outlet communicating with a conduit leading from the compressor to fuel burners associated with the boilers, and a forced LNG vaporiser having an inlet communicating with a liquid storage region of the said tank and an outlet communicating with the same or a different conduit leading to fuel burners associated with the conduit. The forced gas vaporiser is able to supplement the fuel provided by natural boil-off of the liquefied natural gas.
In principle, the apparatus according to EP 1 291 576 A may be adapted to supply fuel for any need on board the ship. Some modern LNG tankers employ engines that can be run on either diesel or natural gas. The presence of higher hydrocarbons in the natural gas can, however, cause the engine to knock.
The present invention relates to a method and apparatus that address this problem.